<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .divbox{
            border: #1E9FFF 1px solid;
            box-sizing: border-box;
        }
        html,body{
            width: 100%;
            height: 100%;
            padding: 0;
            margin: 0;
        }
    </style>
</head>
<body>
<!-- 你的容器 -->
<div id="yourContent" style="width: 800px;height: 500px;border: black 1px solid">

        <div class="divbox" style="height: 10%;width: 100%;"></div>


        <div class="divbox" style="width: 100%;height: 80%"></div>

        <div class="divbox" style="height: 10%;width: 100%;"></div>

</div>
</body>
</html>